Internal-combustion heater with air-heating tubes



MEE

.oct 19, 194s.

H. J. DE N MGCQLLUM INTERNAL-consumos HEATER WITH ATR HEATING TUBES Fina Aprii 5. 1945 lli lil@

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2 Shqet'sfSheet v1 'I All Oct. 19, 1948. H. J. DE N. MccoLLQM" 2,451,623

l' :mmm-consusnon HEATER WITH AIR mum mss. Filed April 5. 194s i zsnqdtsf'sneerz Patented Oct. 19, 1948 INTERNAL-COMBUSTION HEATER WITH AIR-HEATING TUBES HenryJ. De N. McCollum, Chicago. lll.: Thelma McCollum, exeoutrix of McCollum, deceased.

said Henry J. De N. assigner to Stewart-Warner Corporation, Chicago, Ill., a corporation of Virginia Appuemsn April s, im, semi No. usas s claims. (el. 12s-10s) My invention relates toheaters and more particularly to heaters ol' the type used to heat the cabins or other spaces of airplanes or for similar purposes.

An object of my invention is to provide a heater having a new and improved heat exchanger.

Another object oi' my invention is to provide a heater having' anew andimproved combustionchamber. f

Another obiectoi.' my invention is to provide a new and improved heater which is highly eniclent. light in\weight and which may be easily and inexpensively manufactured.

Other obiects and advantages will become apparent as the description proceeds.

In the drawings:

Fig.' i is a longitudinal, sectional view oi a heater embodying my invention and .is taken generally along the line i-I oi Fig. 4, but has certain parts cut away to show detailsv of construction o! the tubing oi the heat exchanger and the shell 'of the muiiier; y

Fig. 2 is atop plan view on a reduced scale ci the heater of Fig. 1 and a blower ior supplying' air thereto, parts being cut away lto show the detail of the heat exchanger and induction tube therefor:

Fig. 3 is a' transverse. sectional view taken on the line I- oi' Fig. 1;,

Fig. 4 is an irregular. transverse. sectional viewA taken on the line 4-4 of Fig. 2;

Fig. 5 is a partial view similar to Fig. 3, but showing a modified form o1 my invention;

Fig. 6 is a perspective view oi a part of one oi the pipe supporting rings of the heat exchanger;

Fig. 7 is a view showing one step in the assembly of the heat exchanger; and

Fig. 8 is a view showing a subsequent step inf other suitable source of air supplymay be provided in lieu oi the blower shown in this figure. As best shown in Fig. 1, this heater comprises a combusion chamber il having an end wall i and a cylindrical wall 2l attached to one end of a heat exchanger by-bolts 2.4. or any other suitable means. The combustion chamber il land the heat exchanger 22 are attached to a cylindrical casing 2l, by straps il and one end of this casing il has a tapered inlet Il connected to the blower i2.

'I'he heat exchanger 22 comprises a pair o! supporting rings-II and il and a plurality of tubes 2 It mounted thereon. As best shown in Figs. 3 and 4, the tubes l0 are arranged in theform of a cylinder andthe contacting walls of adjacent tubes are welded or soldered together, as iridi-k cated at Il. so that the entire bundle of tubes forms an air tight cylinder.

A convenient and suitable method of making the heat exchanger 22 is indicated in Figs. 6, 7

and 8. In Fig. vil, I have shown a ring 32 before l0 the tubes are mounted therein. This ring has a cylindrical inner wall lil and a scalloped outer wall I! having semi-cylindrical depressions M having radii equal to the radius of the outer wall o! thev tubes Il. A pair of rings identical with l5 the ring l2 is placed in spaced relationship and a plurality of tubes is positioned about these rings with the ends of the tubes in the semi-cylindrical recesses It. as indicated in Fig. 7. Recesses M are so spaced that when tubes are mounted in these recesses. the side walls of the tubes contact each other, asl clearly shown in Fig. '1. While vthese tubes are held in this position. their contacting walls are welded or soldered together to form a unitary cylindrical structure and the ends of these tubes are welded or soldered to the rings Il and Il. After this welding operation has been completed. the heat exchanger is placed in a lathe or similar machine and the rings are turned down 80 so that the inner walls of these rings have the same diameter as the innermost portions oi the walls of the4 tubes In other words. the rings are turned down :from the size shown in Figs. 6 and 7 to that shown in Fig. 8. The purpose of 35 turning down the rings in this manner is to per--v mit a muiller ireely to be slid in and out of the heat exchanger in a manner to be hereinafter described.

The tubes Il form a scalloped. cylindrical.

divided into a plurality of compartments by partitions Il. These compartments are illled with sound absorbing material l2, such as glass wool' or stainless steel wool and perforations Il in the muiller shell provide acoustic couplings between the interior of these compartments and the gas passages It formed between the mui'lier shell and .the tubes 3l.

The end wall Il of the munier has attached thereto. by bolts ll. or in any other suitable manner. a heat insulating disc l2 of refractory or other suitable material which serves to protect the sound absorbing material against the intense ss heat ot the combustion chamber.

The muffler 46 may be freely inserted into or removed from the heat exchanger 22. muiller lssecured in position in the heat exchanger by a bolt 64 attached to the end Aplate 66v of the mufer. This bolt 64 has a reduced threaded end l88 which passes through a sleeve mounted in an opening in the wall ofan exhaust tube.12, the bolt being secured to this sleeve'by a nut 14. The tube 12 is bolted or otherwise secured to a plate 16 bolted to the ring 84 of the heat exchanger.

The casing 26 has a tapered outletV end 18 terminating in a short, ycylindrical section 80 which may discharge heated air directly into an airplane cabin or other space to be heated or may be connected to a duct system for delivering this heated air to one or more outlets arranged in' the same or different spaces. A carburetor air inlet pipe 82 has one end attached tothe tapered outlet 18 and diverts part of the air which has passed over the heater into a carburetor 84 located outside of the casing 26. Pipe 86 conn'ects the carburetor 84 with any suitable source of fuel and an induction tube 88 conducts` the fuel and air mixture formed in the carburetor 84 to the combustion chamber I6. This induction tube has a reversely curved portion 90 leading to a long, straight end 82, which extends through the casing 26 and into the lower portion of the combustion chamber. All parts of the induction tube 88 preferably lie in the same horizontal plane and the straight end of this tube is given a length substantially seven times the interna1 diameter of this tube in order that the flow of fuel and air in different parts of the cross section of this tube will be substantially uniform at the point where the tube discharges into the combustion chamber.

'I'hat portion of the induction tube which lies within the combustion chamber receives heat This1 from the combustion in this chamber and serves to preheat the fuel and air mixture delivered to this chamber. This portion of the induction tube extends across the lower portion of the combustion chamber in a direction perpendicular to the axis of this chamber so that mixture delivered by this tube tends to whirl about the axis of the combustion chamber and form a ring of llame therein when ignited by an electrical igniter 94 located in a pocket 96 whichis outside of the combustion-chamber but connected thereto by way of inlet 88 and outlet |00. The particular construction 'and arrangement of the induction tube and igniter are claimed in my co-pending 25, 1943, now Patent No. 2,433,618, Serial No. 477,081, iiled February 25, 1943, now Patent No.

2,390,380, and Serial No. 484,971, illed April 29,

1943, now Patent No. 2,405,317.

After the heater has been in operation for an appreciable length of time, the air supplied to theV carburetor 8l becomes heated and this heated air prevents the formation 'of ice in the carburetor and also assists in vaporization of fuel supplied to this air by the carburetor jet. vWhen the heater is first started. however. the air supplied to the applications, Serial No. 477,080, illed FebruaryV |02 which is attached to the circular wall ofthe combustion chamber, as by welding or any other suitable manner, and which serves to direct into the inlet 88 of the igniter pocket any liquid fuel or particularly rich mixture of fuel and air discharged from the induction tube 82. 'I'hat end of the l,ring |02 which is adjacent the induction tube 92 is spaced from the rear wall I8 of the combustion chamber a distance substantially equal to the outside diameter of the induction tube, whereas the other end of this ring lies adjacent the igniter pocket 86 and is spaced from the wall I8 a distance substantially equal to thc width of the inlet and outlet which connect this pocket with the combustion chamber. After the heater is in operation, this ring insures that'any liquid fuel delivered to the combustion chamber will be vaporized and burn before it leaves this chamber.

The hot productsof combustion flowing from the open righthand end of the combustion chamber 6 ar'e directed by the muilier 46 into the gas passages 66 formed between the muiiler shell and the tubes 86. As the hot gases flow along these passages, these gases give up their heat to the walls of the Atubes 86 and the cooled products of combustion leave the righthand ends of the passages 66 and enter an outlet chamber |04 formed between the righthand end o f the mufiler and the plate 16. 'I'hese cooled gases then pass to atmosphere through discharge tube 12 and any suitable exhaust pipe which may be attached thereto. Sound entrained in the hot products of combustion enters the muiller shell through perforations 68 and is absorbed by the sound absorbing material contained in the several compartments of the muffler.

Air supplied to the heater by the blower I2, or by any other suitable airsupply. means, passes around the combustion chamber I6 and absorbs some heat from the walls of this chamber. Part of this air then enters the lefthand ends of the tubes 36 of the heat exchanger while the remainder of this air enters the space |06 between these tubes and the casing 26. As the air iiows lengthwise of the heat exchanger, this air absorbs heat from the walls of the tubes 36 which function like fins to transfer heat from the hot products of combustion to this air.

-In the embodiment of Figs. l to 4, inclusive, thc tubes v3|; are provided with webs |08 which divide the tubes into two sections and facilitate the transfer of heat to the air owing through these tubes. In the embodiment of Fig.v 5, the tubes 36' are not provided with such webs, but in other respects the embodiment of Fig.v 5 is identical with that of Figs. 1 to 4, inclusive.

Most of the heated air passes from the heat ex' lchanger is formed are preferably of material having a high heat conductivity, such for example as cOpDer or aluminum. since the walls of these tubes act as fins to transfer heat from the hot products of combustion to the Ventilating air. Where these tubes are provided with webs like the webs |08,

these webs should also preferably be of materia1 tubes which are already coated with aluminum metal alloy which melts at a temperature approximately 40 below the melting point of alurn'i- 5 num.

The heat exchanger can be readily made by cutting these commercial tubes tothe desired length, stackingsuch tubes in the supporting rings 32 and 2. A heater of the class described, comprising a heat exchanger composed of a cylindrically arranged series of contacting cylindrical tubes longitudinally extending in side by side con-tacting relationship and having their contact portions secured to each other to form a gas tight tubular structure, a cylindrical muiiler located in said-heat exchanger in spaced relation thereto and cooperating with said tubes to form gas pass-ages lon- 34, in the manner indicated in Fig. 7, placing a\,10 gitudinally of said heat exchanger, means formband around the tubes to hold them in this assembled relationship, bonding the tubes with a suitable ilux at the points where the interior walls oi these tubes engage each other, and placing the assembly in an oven maintained at a temperature between the melting point of the welding material and the meltingpoint of aluminum. After the assembly has been kept in the oven .the desired length of time, it is removed and cooled, at which time the tubes will be welded into a solid mass which is rigid and self-supporting. 'I'hereafter the supporting rings can be turned down, as indicated in Fig. 8, to complete the heat exchanger.

While I have described my invention as being particularly adapted for heating the cabins of aircraft, it is not limited tov such use and is capable of general application. It is to be understood that my invention is not limited to the particular details shown and described herein, but may assume numerous other forms and that the scope of my invention is defined in the following claims.

1. A heater of the class described, comprising a heat exchanger composedpof a plurality of individual tubes vlongitudinally extending in side by side contacting relationship and having their contacting portions secured to each other to form a gas tight tubular structure, said tubes having webs therein, each/web having opposite edges secured tofthe walls of its tube throughout subl stantially the length of said tube, means forming a. combustion chamber for supplying hot products of combustion to the interior of said ltubularl ing a combustion chamber for supplying hot products of combustion to one end of said passages, and means for directing .Ventilating air over said combusti-on chamber means ,and through said tubes.

the ends of said tubes in scalloped portions of said peripheries and the side wallsbf adjacent tubes in contacting engagement with each other, securing the contacting walls of said ,tubes to each other and 4securing said tubes to said rings, and

removing the internal diameters of said rings to REEERENCS CITED u The following references are of record in the le of this patent:

UNITED sTA'rEsPATENTs' Number Name Date 116,731 nonnen Jan. 3, 1871 217,723 Beecher July 22, 1879 1,770,208 Keinrial July 8, 1930 2,000,906 Turner May 14, 1935 2,097,255 Saha Oct. 26, 1937 2,119,451 Turner May 31, 1938 2,249,977 Uschoid et al. July 1, 1941 2,362,271 I Heymann Nov. 7, 1944 FOREIGN PATENTS Number Country Date 1,003 Great Britain Jan. 20, 1891 548,067

Germany Nov. 19, 1929 

